This domain can be found in caspases (MEROPS family C12A) and metacaspases (MEROPS family C14B). Metacaspases adopt a caspase fold, with active site loops arranged similarly as other caspases [].Caspases (Cysteine-dependent ASPartyl-specific proteASE) are cysteine peptidases []. They are tightly regulated proteins that require zymogen activation to become active, and once active can be regulated by caspase inhibitors. Caspases are mainly involved in mediating cell death (apoptosis) [, , ]. They have two main roles within the apoptosis cascade: as initiators that trigger the cell death process, and as effectors of the process itself. Caspases can have roles other than in apoptosis, such as caspase-1 (interleukin-1 beta convertase) (), which is involved in the inflammatory process. The activation of apoptosis can sometimes lead to caspase-1 activation, providing a link between apoptosis and inflammation, such as during the targeting of infected cells. Caspases may also be involved in cell differentiation [].Metacaspases are arginine/lysine-specific, in contrast to caspases, which are aspartate-specific. They are found only in plants [, ], fungi []and lower eukaryotes, including the protozoa []. While plant metacaspases have been shown to be involved in cell death pathways, in other organisms they have evolved alternative functions [].

This database is part of a project that received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement number 649024).